根据实验得出,session中存放的对象仅仅是存放的引用而已,如果把对象取出来后,修改值,并不需要重新放入session中,如
ActivityInfo activityInfo = new ActivityInfo();
activityInfo.setActivity_code("0908");
session.setAttribute("activityInfo", activityInfo);
ActivityInfo a =(ActivityInfo) session.getAttribute("activityInfo");
a.setActivity_code("0909");
ActivityInfo b =(ActivityInfo) session.getAttribute("activityInfo");
System.out.println(b.getActivity_code());
执行后取出的将会是0909,但是如果存放的是string类型这种final的话就必须重新放入